JPH09318308A - Method for measuring clearance distance between members and method for controlling electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clearance distance measuring method which calculates a clearance distance between members such as that between a roller and a photosensitive body in a wet type electrophotographic apparatus. SOLUTION: In this method, when a member B identical to a member A as electric resistor or conductor is set with a fine clearance made from the surface of the member A, a clearance distance between the members A and B is calculated from a voltage-current characteristic previously in a fixed relationship. To be more specific, an electrophotographic apparatus has a system in which a voltage is applied to a roller-shaped member B (such as set roller 4) set at a fixed distance from a photosensitive body 1 as member A. In this case, a discharge start voltage is determined by measuring the voltage applied to the roller-shaped member and the current flowing utilizing a fixed relationship existing between the clearance distance between the photosensitive body and the roller-shaped member and the discharge start voltage and a distance between the photosensitive body and the roller-shaped member is measured from a relational expression previously computed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a gap distance between members applied to a gap distance measurement between members in a wet electrophotographic apparatus, and a gap distance between members obtained by the measuring method. The present invention relates to a control method of an electrophotographic apparatus that controls a related process. The present invention is also 1 m
In the field where it is difficult to directly measure the voids in an ultra-precision mechanical device that is assembled by providing voids of m or less or several μm order, the distance between members such as metal is measured by applying voltage without using spacers, etc. , Non-contact roller electrification, non-contact static elimination, etc., in a device that applies a physical phenomenon that causes a discharge phenomenon by applying a voltage with a narrow gap between objects, the gap distance is the discharge start voltage. It can be applied to a device for measuring and controlling from.

[0002]

2. Description of the Related Art In a wet electrophotographic apparatus to which the present invention is mainly applied, a developing roller (supplying a developing solution for developing a latent image on the photosensitive member) and a reverse roller are provided around the photosensitive member. Roller (used to remove excess developer), set roller (used to electrically increase the binding force of the toner image on the photoreceptor)
Etc. are arranged, and each roller is installed with a very small gap between it and the photoconductor. It is an essential matter to obtain a good image output by accurately setting the gap distance between these rollers and the photoconductor. For example, if the distance between the roller and the photoconductor is too short, the toner image formed on the photoconductor is scraped by the roller, and if it is too far away, the excess developer cannot be removed sufficiently.

Although it is possible to accurately measure the outer shape of each of the rollers and the photoconductor at the time of making the photoreceptor and obtain the air gap distance by calculation, it is necessary to calculate one by one for each set, which is difficult in mass production of machines. In addition, the gap distance may change during replacement due to the accuracy error of the photoconductor. Therefore, it is desirable to be able to measure in the actual machine if possible. However, since these rollers are continuously arranged around the photoreceptor (see FIG. 1), it is difficult to measure with a gap gauge or the like, and for the same reason, it is also possible to use a non-contact laser outer diameter measuring device or the like. difficult. Therefore, it has been difficult to measure the air gap distance in an actual machine.

[0004]

When the objects are placed at a certain distance from each other and a voltage is applied between the objects, while the applied voltage is low, the current is not applied between them. It does not flow, but when the applied voltage is gradually increased, a certain amount of current suddenly starts to flow. The voltage at which this current begins to flow is called the discharge start voltage, and it is known that there is a certain relationship between the discharge start voltage and the distance between objects (Paschen's law).

Generally, there are a stable discharge state before and after the start of discharge (glow-like discharge) and an unstable state of shifting to spark discharge. The present application can be applied to either discharge form. Can be measured more accurately. The discharge current during this discharge is a harmonic current, but at the time of actual measurement, the average current is observed with an analog ammeter using a detection resistor. Also, if a capacitor is inserted in parallel with the resistor in order to cut harmonics and then observed, the same average current can be obtained. The current in the following description refers to this average current.

In the present invention, attention is paid to the Paschen's law described above, a voltage is applied between two bodies, and the discharge start voltage is measured to measure the minute air gap distance. Voltage is applied to the roller, the discharge start voltage is obtained, and the gap distance between the photoconductor and the roller is calculated from the discharge start voltage. Further, it is an object to perform control based on the calculated gap distance so that processes such as developing solution supply and excess developing solution removal, which depend on the distance between the roller and the photoconductor, can be stably performed.

That is, the present invention takes advantage of the fact that the discharge phenomenon between voids has a physical phenomenon that discharge is started at a certain voltage (discharge start voltage) when the applied voltage is gradually increased, and the voltage is applied to the roller. The discharge start voltage between the roller and the photoconductor is applied by applying the method to provide a gap distance measuring method between members for calculating the gap distance between the roller and the photoconductor, and from the calculated gap distance. An object of the present invention is to provide a control method for an electrophotographic apparatus that controls electrophotographic processes related to them.

[0008]

According to the first aspect of the present invention,
A method for measuring a gap distance between members, wherein when a member B similar to A is installed with a minute gap from the surface of a member A which is an electric resistor or conductor, a voltage having a constant relation- The air gap distance between the members A and B is calculated from the current characteristics.

According to a second aspect of the present invention, there is provided a member in an electrophotographic apparatus having a system for applying a voltage to a roller-shaped member B installed at a constant distance from the photosensitive member which is the member A. In the method for measuring the air gap distance between the photoconductor and the roller-shaped member, the fact that there is a constant relationship between the discharge start voltage, the voltage applied to the roller-shaped member and the flowing current The discharge start voltage is obtained by measuring the above, and the gap distance between the photoconductor and the roller-like member is measured from the relational expression calculated in advance.

According to a third aspect of the present invention, a member in an electrophotographic apparatus having a system for applying a voltage to a roller-shaped member B installed at a constant distance from the photosensitive member which is the member A. In the method for measuring the air gap distance between the photoconductor and the roller-shaped member, the fact that there is a constant relationship between the discharge start voltage and the gap distance between the photoconductor and the predetermined voltage applied to the roller-shaped member flows. A certain relationship (relational expression (C)) with the current relationship is calculated in advance, and a typical voltage-current relationship at one or several points that represents the characteristics is measured. The discharge start voltage is calculated by applying it, and the gap distance between the photoconductor and the roller-shaped member is measured from the relational expression (D) calculated in advance.

According to a fourth aspect of the present invention, in the method for measuring the air gap distance between members according to the first, second or third aspects, when the object of measurement is the air gap distance between the members in the wet electrophotographic apparatus, development is performed at the time of measurement. Stop the replenishment of the agent, etc., and make the distance a void, and measure.

The invention according to claim 5 is the invention as claimed in claims 1, 2, and 3.
Alternatively, in the method for measuring the gap distance between members described in 4, the photoreceptor and the roller, which are member A, or the roller-like member B, or the gap between the members is divided or restricted into a plurality of regions in the axial direction, and the measurement is performed. The distance to the member is measured with high accuracy in the axial direction.

According to a sixth aspect of the present invention, there is provided a method of controlling an electrophotographic apparatus, which has a system for applying a voltage to a roller-shaped member installed at a fixed distance from a photoconductor. In the electrophotographic apparatus, the gap distance between the developing roller and the photoconductor, which is located around the same photoconductor as the roller-shaped member that causes discharge, is measured by the measuring method according to any one of claims 1, 2, 3, 4, and 5. When the determined distance is uniquely determined by the gap distance between the roller-shaped member and the photoconductor, the rotation speed of the developing roller is determined from the relational expression calculated in advance using the obtained distance.

According to a seventh aspect of the present invention, there is provided a method for controlling an electrophotographic apparatus, which has a system for applying a voltage to a roller-shaped member installed at a fixed distance from a photoconductor. In the electrophotographic apparatus, the gap distance between the photoconductor and the reverse roller around the photoconductor that is the same as the roller-shaped member that causes discharge is measured by the measuring method according to any one of claims 1, 2, 3, 4, and 5. When the determined distance is uniquely determined by the gap distance between the roller-shaped member and the photoconductor, the rotation speed of the reverse roller is determined from the relational expression calculated in advance using the obtained distance.

An eighth aspect of the present invention is a method for controlling an electrophotographic apparatus, which has a system for applying a voltage to a roller-shaped member installed at a fixed distance from a photoconductor. In the electrophotographic apparatus, after the photoconductor, the roller-shaped member, and the like are exchanged, the gap distances of these are set as claimed in claims 1, 2, 3,
Measurement and adjustment by the measurement method according to any one of claims 4 and 5 and control by the control method according to claim 6 or 7 are automatically performed.

The invention according to claim 9 is based on claims 1, 2 and
In the method for measuring the gap distance between members described in 3, 4, or 5, not only the measurement inside the electrophotographic apparatus but also the distance between the members at the time of external production or inspection, and the accuracy measurement of each component is measured. And so on.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the construction of a developing section of a wet electrophotographic apparatus in which the present invention is carried out. In FIG. 1A,
The three rollers arranged around the photoconductor (PC) 1 are a developing roller (DR) 2, a reverse roller (RR) 3, and a set from the upstream side in the rotation direction (arrow direction in the figure) of the photoconductor 1 respectively. The roller (SR) 4. Each of the rollers 2, 3 and 4 has a distance of 50 to 1 between it and the photoconductor 1.
They are arranged with gaps (Gap) G _DR , G _RR , and G _{SR of} about 00 μm. The gaps G _DR , G _RR , and G _SR are determined by the bearing 6 mounted coaxially with the roller portion 5 of each roller at the roller end, as shown in FIG. 1B. The outer peripheral surface is in contact with the raw tube portion 1b at the end of the photoconductor. Therefore, this bearing 6
The difference between the outer diameter of the photosensitive member 1 and the outer diameter of the roller portion 5 and the step between the photosensitive layer 1a of the photosensitive member 1 and the raw tube portion 1b at the end portion of the photosensitive member determine the gap distance between the photosensitive member 1 and the roller portion 5. ing. Of these three rollers, a developing bias is applied to the developing roller 2 and a set voltage is applied to the set roller 4. Of these, the set roller 4 has a high applied voltage, and therefore discharges to the surface of the photoconductor.

Next, the concept underlying the present invention will be shown. FIG. 2 shows an example of discharge characteristics between a roller (for example, a set roller) and a photoconductor. The horizontal axis represents the voltage V applied to the roller, and the vertical axis represents the current I flowing at that time. As shown in FIG. 2, when the applied voltage is gradually increased, a current starts flowing at a certain point. This voltage is called the discharge start voltage Vs. After that, when the applied voltage is increased, the current also increases with a slope θ, but the curve depends on the material of the roller, the material of the surface of the photoconductor, and the circuit constant of the circuit to which the voltage is applied. Therefore, it is indicated by a straight line). Here, the inclination θ is a parameter determined by the roller material, the resistance of the photoconductor, and the like, and the discharge start voltage Vs is a parameter determined by the gap (Gap) between the roller and the photoconductor. It should be noted that such a phenomenon is not limited to the photoconductor and the roller, and is a phenomenon that occurs regardless of the material and the material having any shape. It can be said that this technology can be applied to various fields such as distance measurement.

It should be noted here that since the photosensitive member is a semiconductor and has a relatively high resistance, the corresponding rollers can stably start discharging even a low resistance member such as a metal conductor. Further, when the gap is relatively large as 500 μm, stable discharge occurs when the surface resistance of the roller is high or a high resistance body is inserted in the circuit. Further, if the gap is 50 μm or less, the discharge starting voltage becomes stable without depending on the resistance of the roller. In addition, insert a high-resistance element in the circuit between the non-photosensitive member and the metal surface (insert it in series with the resistance of the air gap).
However, the gap can be adapted to 100 μm or less. Of course, if a metal oxide film, which is a high resistance material, is present on the surface of the roller, there will be a great margin in measuring the voids. Incidentally, FIGS. 3, 4 and 5 show data obtained by actually measuring how the inclination of the voltage-current characteristics changes depending on the roller type, circuit resistance, etc. of the set roller (SR) as an example. 3 is an example of a set roller having a hard alumite coating, FIG. 4 is an example of a metal roller, and FIG.
Shows an example of a roller coated with a TiO ₂ (10%) sprayed coating, and shows the case where a resistor is not connected to the circuit and the case where it is connected.

Here, the discharge starting voltage is a parameter determined by the gap distance between the objects. This relation is called Paschen's law, and in the region where the gap distance is 10 μm or more, the relation between the gap distance and the discharge start voltage can be approximated by a linear expression (see FIG. 6). Therefore, if the discharge starting voltage can be obtained, the distance between the objects can be obtained (Claim 1). Further, in the case of this example, it is possible to obtain the gap distance between the photoreceptor and each roller in the electrophotographic apparatus (claim 2).

There are several methods for obtaining the discharge start voltage. First, as shown in FIG. 7A, while monitoring the amount of current flowing from the power supply, the applied voltage is gradually increased from the lower voltage side, and the voltage at which the current has flowed out is obtained to determine the discharge start voltage Vs. And how to. The other is Figure 7 (b).
As shown in FIG. 5, a voltage that causes a certain amount of discharge is first applied, and then the voltage is gradually lowered to obtain a voltage at which discharge stops and no current flows and the discharge start voltage Vs is obtained. When the discharge start voltage Vs is obtained in this way, the gap distance between the photoconductor and the roller member can be obtained by applying the Paschen's equation in the actual machine that is known in advance (for example, from the relationship of FIG. 6).

Although these methods are simple, a minute current must be detected when the current starts to flow or stops flowing, and an amplifier is required, and the voltage must be gradually raised or lowered. Technical costs are involved, such as having to add a scanning circuit for the applied voltage.

Therefore, a method according to claim 3 in which that point is improved will be described. The relationship between the applied voltage (V) and the current (I) is uniquely determined depending on the material of the roller, the material of the surface of the photoconductor, and the circuit for applying the voltage. Therefore, if the discharge start voltage is Vs, this relational expression can be expressed as V = f (I) (relational expression (C) described in claim 3). Here, when I = 0, that is, V when f (0)
Becomes Vs. Therefore, by utilizing this relationship, FIG.
As shown in (a), the current I flowing when a voltage V is applied is measured at several points, and the relational expression V = f (I) is obtained by fitting, and the discharge start voltage ( Vs = f (0)) is calculated. That is, FIG.
In the above example, since f (I) is approximated by a linear function, V = a × I + Vs (a is a coefficient obtained from the slope of the straight line) and V = Vs when the current I = 0. After that, the void distance can be calculated from Paschen's equation (relational expression D in claim 3) as in claim 2. It should be noted that FIG. 8B is a diagram showing an example of voltage-current characteristics when fitting is performed by a high-order (second or higher order) function.

Next, in the examples shown in FIGS. 9, 10 and 11, as the above-mentioned set roller, a hard alumite film or a metal oxide sprayed film (TiO ₂ 10 in the illustrated example) is used.
Using a roller made of aluminum with (% sprayed film),
It shows the current that flows when a voltage is applied and the roller is placed at a distance shown in the drawing from the photoconductor. V = f (I) is almost a linear function for a roller having a hard alumite film, and a roller having a metal oxide sprayed film has a voltage-current characteristic that can be approximated by a quadratic function, and its slope is It is almost constant regardless of the air gap distance. Therefore, if the curve functions of these slopes are known in advance, it is possible to find the discharge start voltage Vs by fitting them to the function only by measuring representative points.

9 to 11 are graphs obtained from data obtained by measuring the voltage-current characteristics by shaking the air gap distance (discharge gap) between 50 μm and 200 μm with a hard alumite coating roller or a metal oxide sprayed coating roller. Since the point at which I = 0 is the discharge start voltage in each graph, the relationship between the discharge start voltage and the air gap distance can be obtained from the graphs of FIGS. Therefore, if the discharge start voltage is obtained, the air gap distance can be obtained from these figures.

The embodiment described here relates to the measurement of the gap distance between the photosensitive member and the roller member of the wet electrophotographic apparatus. However, in the case of the wet electrophotographic apparatus, the developing solution is accumulated in the gap, so that it is accurate as it is. It is difficult to get the gap distance. Therefore, when applying the present invention to a wet electrophotographic apparatus, it is important to stop the supply of the developing solution in advance so that the liquid does not exist between the roller and the photoconductor (Claim 4). .

The above-mentioned measuring method can be carried out with the photosensitive member and the roller stopped, or with one or both of them being rotated, but the discharge phenomenon is used. Since the discharge in the rotating state can be measured without deteriorating each member, the discharge in the rotating state is preferable to the discharge in the stationary state. In that case, the obtained void distance becomes average. Further, when the measurement is performed in a stationary state, each distance represents the nearest neighbor distance at the measurement position.

The measurement accuracy in the axial direction can be improved by dividing or limiting the photosensitive member or the roller or the gap between them in the axial direction.
For example, as shown in FIG. 12, a jig drum dedicated to measurement is prepared in which only one part is a conductor (or semiconductor) and the other part is a non-conductor (high resistance insulator, etc.), and the jig drum is used for measurement. It is conceivable to insert a high-resistance Mylar film or the like into a space other than the place to be measured between the photoconductor and the roller as shown in FIG. 13 and measure only the target position. The distance between the photoconductor and the roller member can be measured with high accuracy in the axial direction. (Claim 5)

In the developing section of the wet electrophotographic apparatus of this embodiment, the three rollers 2, 3 and 4 are arranged around the photosensitive member 1 as shown in FIG. By measuring the relationship between the roller bearing diameter and the roller diameter, when the photoconductor and each roller are installed, if the air gap distance between one roller and the photoconductor is known, the remaining two air gap distances can be obtained. To be For example, the set roller (SR) 4 and the photoconductor 1 are measured by measuring the gap distance by the above-described measuring method.
If the distance between the photoconductor 1 and the developing roller (DR) 2 or the reverse roller (RR) 3 is known, the distance between the photoconductor 1 and the developing roller (DR) 2 is also known.

Here, as shown in FIG. 14, the gap distance between the developing roller (DR) 2 or the reverse roller (RR) 3 and the photoconductor 1 is important for determining the developer supply amount and the excess liquid removal amount, respectively. This is a parameter, and it is common to change the rotation speed of the roller in order to keep the amount constant when the air gap distance changes. For example, the amount of developer supplied to the photoconductor 1 is determined by the number of revolutions of the developing roller (DR) 2 and the gap distance between the photoconductor 1 and the developing roller (DR) 2, and when the distance changes, the number of revolutions is changed to develop. The liquid supply amount can be adjusted to be constant. Similarly, in the case of the reverse roller (RR) 3, the amount of excess liquid removed is determined by the gap distance between the photoconductor 1 and the reverse roller (RR) 3 and the rotation speed of the reverse roller (RR) 3. As described above, since there is a fixed relationship between the void distance and the developer supply amount or the excess liquid removal amount, the void distance between the set roller 4 and the photoconductor 1 is measured by the void distance measuring method as described above. Then, if the gap distance of the developing roller 2 or the reverse roller 3 is calculated from the gap distance, the rotation speed of the developing roller or the rotation speed of the reverse roller is determined from the relational expression calculated in advance using the obtained distance. Therefore, these processes can be controlled to an optimum state (claims 6 and 7). Therefore, when the photoconductor is replaced, or when any of the three rollers is replaced, the positional relationship between the rollers is not required to measure the outside diameter of the rollers, etc. And the process can be controlled.

Further, according to any one of claims 1, 2, 3, 4, and 5, the control unit (comprising a microcomputer, a memory, and various control circuits) in the actual machine of the wet electrophotographic apparatus is provided with an empty gap distance. If a program that can automatically perform measurement and adjustment according to the measurement method described above and control according to the control method according to claim 6 or 7 is prepared in advance, parameters will be automatically set when the photoconductor or roller member is replaced. Since the resetting can be performed, the maintenance time is omitted and the productivity is improved (claim 8).

Further, in the present invention, the above-described method for measuring the gap distance between members is performed not only by measuring inside the electrophotographic apparatus but also by measuring the distance between members during external production or inspection. It is applied to the accuracy measurement of parts of. That is, these methods can be a method of simply measuring the air gap distance not only in the actual machine but also in the production site of roller members and photoconductors, finish inspection, etc., and improve the productivity of accuracy measurement of parts and It can contribute to the improvement of accuracy (claim 9).

[0034]

As described above, in the method for measuring the gap distance between members according to the first aspect, a member similar to A is provided with a minute gap from the surface of the member A which is an electric resistor or conductor. When B is installed, the air gap distance between the members A and B is calculated from the voltage-current characteristics having a constant relationship in advance, that is, the air gap distance between the members is obtained by using the discharge start voltage as a parameter, and thus non-contact The void distance can be easily measured with.

In the method for measuring the gap distance between members according to claim 2, the gap distance between the photoconductor and the roller-shaped member,
Taking advantage of the fact that there is a fixed relationship with the discharge start voltage, the discharge start voltage is determined by measuring the voltage applied to the roller-shaped member and the flowing current, and the photosensitive formula is calculated from the previously calculated relational expression. By measuring the gap distance between the body and the roller-like member, that is, by obtaining the gap distance between the members using the discharge start voltage as a parameter, it is possible to more easily measure from the outside such as between the photoreceptor and the roller-like member. The air gap distance can be accurately measured even in a place where it is impossible. In addition, since existing equipment (for example, a set roller and its power source) can be used, measurement can be performed at low cost.

In the method for measuring the gap distance between members according to claim 3, the gap distance between the photoconductor and the roller-shaped member,
By utilizing the fact that there is a constant relationship with the discharge start voltage, a constant relationship (relational expression (C)) between the predetermined voltage applied to the roller-shaped member and the flowing current is calculated in advance. Then, a typical voltage or current relationship at one or several points representing the characteristic is measured and applied to the relational expression (C) to obtain the discharge start voltage, and the photosensitivity is calculated from the previously calculated relational expression (D). Measure the gap distance between the body and the roller-shaped member, that is, the applied voltage at the time of discharge depending on the property of the member
This method is more accurate than the method of claim 1 because it is a method of calculating the discharge start voltage by measuring the voltage-current at several typical points by utilizing the fact that the tendency of the current is always constant, and obtaining the air gap distance. The discharge starting voltage can be calculated, and accurate measurement can be performed. Further, although the method of claim 1 is simple, it is necessary to detect a minute current at which the current starts to flow. However, the method of claim 3 measures the current that is already constantly flowing, so that a measurement error is generated. Less and easier to measure.

In the method for measuring the gap distance between members according to claim 4, in the method for measuring the gap distance between members according to claim 1, 2 or 3, the object of measurement is the gap distance between the members in the wet electrophotographic apparatus. In this case, stop the replenishment of developer etc. at the time of measurement and make the distance a void,
It is possible to prevent the occurrence of measurement failure and measurement error due to the developer intervening in the gap, and more accurate measurement becomes possible.

In the method for measuring a gap distance between members according to claim 5, in the method for measuring a gap distance between members according to claim 1, 2, 3 or 4, the member A is a photoreceptor or a roller member B or The distance between the photoconductor and the roller-shaped member can be measured with high accuracy in the axial direction by dividing or limiting the gap between the two in a plurality of regions in the axial direction and measuring. Therefore, it is possible to detect installation failure such as the roller-shaped member being installed at an inclination.

According to a sixth aspect of the present invention, there is provided a method for controlling an electrophotographic apparatus, wherein a gap distance between a developing roller and a photoconductor is the same as that of a roller-shaped member (for example, a set roller) that causes discharge. , 2, 3, 4, 5 uniquely determined by the gap distance between the roller-shaped member that causes the discharge and the photoconductor, which is obtained by the measurement method described in any one of the above items, it is calculated in advance using the obtained distance. When the photoconductor or each roller member is replaced by determining and controlling the rotation speed of the developing roller from the relational expression, the diameter of each roller must be calculated without calculating the diameter of each roller. Process control parameters can be determined, maintenance time can be shortened, costs can be reduced, and stable image output can be obtained.

In the control method of the electrophotographic apparatus according to claim 7, the gap distance between the developing roller and the photosensitive member in the vicinity of the same photosensitive member as that of the roller-shaped member (for example, a set roller) which causes electric discharge is defined by , 2, 3, 4, 5 uniquely determined by the gap distance between the roller-shaped member that causes the discharge and the photoconductor, which is obtained by the measurement method described in any one of the above items, it is calculated in advance using the obtained distance. When the photoconductor and each roller member are replaced by determining and controlling the rotation speed of the reverse roller from the relational expression, the diameter of each roller is not calculated one by one and it is installed in the actual machine. Process control parameters can be determined, maintenance time can be shortened, costs can be reduced, and stable image output can be obtained.

In the control method of the electrophotographic apparatus according to claim 8, after replacing the photoconductor, the roller-shaped member and the like, the void distances of these are set in any one of claims 1, 2, 3, 4 and 5. By automatically performing the measurement and adjustment by the described measurement method and the control by the control method according to claim 6 or 7, it is possible to contribute to shortening the maintenance time and always obtaining a stable image output.

In the method for measuring the gap distance between members according to claim 9, the method for measuring the gap distance between members according to claim 1, 2, 3, 4 or 5 is not limited to the measurement inside the electrophotographic apparatus. By measuring the distance between members during external production or inspection, and applying it to the accuracy measurement of each part, the accuracy of parts can be improved by a simple method even in the case of manufacturing and finish inspection. It can be measured and cost performance can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a developing unit of a wet electrophotographic apparatus in which the present invention is carried out, in which (a) is an arrangement of three rollers of a photosensitive member and a developing unit arranged around the photosensitive member. The figure which shows an example, (b) is a figure which shows the installation example of each roller with respect to a photoconductor.

FIG. 2 is a diagram showing an example of discharge characteristics between a roller and a photoconductor shown in FIG.

FIG. 3 is a diagram showing results of actual measurement of discharge characteristics (voltage-current characteristics) between a roller provided with a hard alumite coating and a photoconductor, with and without a resistor connected to the roller.

FIG. 4 is a diagram showing a result of actual measurement of discharge characteristics (voltage-current characteristics) of a metal roller and a photoconductor when a resistance is connected to the roller.

FIG. 5: Results of actual measurement of discharge characteristics (voltage-current characteristics) between a roller coated with a titanium oxide (TiO ₂ (10%)) sprayed coating and a photoreceptor, with and without a resistor connected to the roller. FIG.

FIG. 6 is a diagram showing a relationship between a gap (Gap) between members and a discharge starting voltage.

FIG. 7 is a diagram showing an example of how to determine a discharge start voltage between members, and a method of determining a point at which the current becomes 0 by gradually increasing or decreasing the applied voltage and setting the discharge start voltage as the discharge start voltage. It is a figure.

FIG. 8 is a diagram showing another example of how to obtain a discharge start voltage between members, in which several points of current flowing when a voltage is applied are typically measured, and a relational expression is calculated based on the measured points. It is explanatory drawing of the method of fitting and calculating | requiring discharge starting voltage.

FIG. 9 is a view showing a result of actually measuring an electric current flowing when a voltage is applied, in which an aluminum roller having a hard alumite film is installed at a distance from a photoconductor and a discharge gap shown in the figure. .

FIG. 10: An aluminum roller having a titanium oxide (TiO ₂ (10%)) sprayed film (thickness: 75 μm) was placed at a distance of the discharge gap shown in the drawing from the photoconductor, and a voltage was applied. It is a figure which shows the result of having measured the electric current which sometimes flowed.

FIG. 11: A roller made of aluminum having a titanium oxide (TiO ₂ (10%)) sprayed film (thickness 100 μm) is placed with a distance between the photoconductor and the discharge gap shown in the figure,
It is a figure which shows the result of having measured the electric current which flowed when voltage was applied.

FIG. 12 is a diagram showing an example of a jig drum dedicated to measurement in which only a part is a conductor (or a semiconductor) and the other part is a non-conductor (high resistance insulator or the like).

[Fig. 13] Installation of a discharge control member such as mylar film in a gap when inserting a high-resistance mylar film or the like into a gap other than a place to be measured between a photoconductor and a roller and measuring only a target position It is a figure which shows an example.

FIG. 14 is an explanatory diagram of supply of a developing solution by a developing roller and removal of an excess solution by a reverse roller in a developing unit of a wet electrophotographic apparatus.

[Explanation of symbols]

 1 photoconductor (PC) 2 developing roller (DR) 3 reverse roller (RR) 4 set roller (SR)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Goo Ikeda 1-3-6 Nakamagome, Ota-ku, Tokyo ・ Inside Ricoh Co., Ltd.

Claims (9)

[Claims] 1. When a member B similar to A is installed with a minute gap from the surface of a member A which is an electric resistor or a conductor, the member A has a predetermined voltage-current characteristic, A method for measuring a gap distance between members, characterized in that the gap distance between B is calculated. 2. A method for measuring a gap distance between members in an electrophotographic apparatus having a system for applying a voltage to a roller-shaped member B installed at a constant distance from a photosensitive member which is the member A. In, the discharge distance is measured by measuring the voltage applied to the roller-shaped member and the flowing current by utilizing the fact that the gap distance between the photoconductor and the roller-shaped member and the discharge start voltage have a constant relationship. A method for measuring a gap distance between members, wherein a starting voltage is obtained and a gap distance between the photoconductor and the roller-like member is measured from a relational expression calculated in advance. 3. A method for measuring a gap distance between members in an electrophotographic apparatus having a system for applying a voltage to a roller-shaped member B installed at a constant distance from a photosensitive member which is the member A. In the above, by utilizing the fact that there is a constant relationship between the gap distance between the photoconductor and the roller-shaped member and the discharge start voltage, the relationship between the predetermined voltage applied to the roller-shaped member and the flowing current is fixed. (Relational expression (C)) is calculated in advance, and a typical one-point or several-point voltage-current relationship representing the characteristic is measured and applied to the relational expression (C) to determine the discharge start voltage. A method for measuring a gap distance between members, wherein the gap distance between the photoconductor and the roller-like member is measured from the relational expression (D) calculated and calculated in advance. 4. A method for measuring a gap distance between members according to claim 1, 2 or 3, wherein when the object to be measured is the gap distance between members in a wet electrophotographic apparatus, supply of developer or the like is stopped at the time of measurement. And measuring the distance by using the distance as a void. 5. The method for measuring a gap distance between members according to claim 1, 2, 3 or 4, wherein the photoconductor as the member A or the roller-like member B or the gap between them is divided into a plurality of regions in the axial direction or A method for measuring a gap distance between members, wherein the distance between the photoconductor and the roller-shaped member is measured with a higher accuracy in the axial direction by limiting the measurement. 6. An electrophotographic apparatus having a system for applying a voltage to a roller-shaped member installed at a fixed distance from the photosensitive member, and the same photosensitive member as the roller-shaped member that causes a discharge. The gap between the developing roller and the photoconductor on the periphery is a gap between the photoconductor and the roller-shaped member that causes the discharge determined by the measuring method according to any one of claims 1, 2, 3, 4, and 5. A control method for an electrophotographic apparatus, wherein when the distance is uniquely determined, the rotation speed of the developing roller is determined from a relational expression calculated in advance using the obtained distance. 7. An electrophotographic apparatus having a system for applying a voltage to a roller-shaped member installed at a fixed distance from the photoconductor, and the same photoconductor as the roller-shaped member that produces a discharge. The distance between the peripheral reverse roller and the photoconductor is a gap between the photoconductor and the roller-like member that causes the discharge determined by the measuring method according to any one of claims 1, 2, 3, 4, and 5. A control method for an electrophotographic apparatus, wherein when the distance is uniquely determined, the rotation speed of the reverse roller is determined from a relational expression calculated in advance using the obtained distance. 8. An electrophotographic apparatus having a system for applying a voltage to a roller-shaped member installed at a fixed distance from the photoconductor, after replacing the photoconductor or the roller-shaped member. , Claims 1, 2, 3, 4, of these void distances
A method of controlling an electrophotographic apparatus, comprising: automatically performing measurement and adjustment by the measurement method according to claim 5 and control by the control method according to claim 6 or 7. 9. A method for measuring a gap distance between members according to claim 1, 2, 3, 4 or 5, wherein the distance between the members is not only measured inside the electrophotographic apparatus, but also during external production or inspection. A method for measuring a gap distance between members, which is characterized by measuring a distance and applying it to accuracy measurement of each component.